John Adalbert Lukacs (; Hungarian: Lukács János Albert; 31 January 1924 – 6 May 2019) was a Hungarian-born American historian who wrote more than thirty books, including Five Days in London, May 1940 and A New Republic.
He was a professor of history at Chestnut Hill College in Philadelphia from 1947 to 1994 and chaired that department from 1947 to 1974.
He served as a visiting professor at Johns Hopkins University, Columbia University, Princeton University, La Salle University, Regent College in British Columbia and the University of Budapest and Hanover College.